In some sense, network interface circuitry to interface a host computer, executing multiple OS's, to a network is known but somewhat limited. For example, for ingress communication (network to host), a Media Access Controller (MAC) within the NIC can be set to accept all layer-2 network packets that arrive at the NIC from the network (promiscuous mode operation) and a network protocol stack within a virtual operating system (VOS), such as provided by Vmware or Xen, on a host computer can then de-multiplex the layer-2 network packets arriving at the host to separate network processing stacks within multiple guest operating systems (guest-OS's) executing on top of the VOS. In other words, the VOS protocol stack forwards unicast packets destined for one or more guest-OS's, and also multicast and broadcast packets, but drops unicast packets that are not destined for any of the guest-OS's. For egress communication, the guest-OS's accomplish sending packets by copying from memory associated with a particular guest-OS to memory associated with the VOS generally, and the VOS then operates to send the packets.
With the recent advances in networking speed, it has become possible to foresee a “unified wire” approach to connectivity. From a network connectivity perspective, it is typical to have in one computer system different NICs for different applications. For example, it is usual to need an Ethernet NIC for general network and Internet connectivity, a Fibre Channel NIC for storage connectivity and a specialized high speed interconnect NIC for high performance computing connectivity. In particular, the Ethernet technology has recently reached speeds high enough to enable the support of these different applications simultaneously over one “multi-function” NIC. The benefits of unifying the “wire” are numerous, including but not limited to the single NIC and single network cost savings as well as the simplified management. However, in-order to preserve the useful characteristics and match the performance of specialized storage and high performance computing networks, it is desirable to enhance the capabilities of the unified wire, for example, to support the storage protocols iSCSI and the Network File System (NFS), and Remote Direct Memory Access (RDMA). In addition, it is needed to provide control on the resource usage of each application type within the unified wire.
For both the egress and ingress direction, the NIC can optionally offload the processing of some network protocols. For example, the protocol offload processing may be according to a Transmission Control Protocol (TCP), whereas communication across the network (layer-2) may be via high-speed Ethernet, such as 10 Gbps Ethernet.